Sheetrock is a trade name for drywall or wall board used in residential home or commercial building construction. It is typically a pre-hardened plaster of Paris, also known as gypsum. It is sold in large sheets and applied as an interior wall surface. In one particular application, sheetrock is used in the ceiling in large sheets or as ceiling tiles. This material is relatively rigid and allows various light fixtures of difference sizes and weights to be attached to it due to its strength. One type of light fixture is a recessed fixture that installs into a hole created in the sheetrock. The light fixture hardware such as the junction box, housing, support legs or clips are hidden behind the ceiling. From below looking up to the installed fixture, the light source (e.g., incandescent bulb, LED cluster, fluorescent tube, etc.) with or without a lens or diffuser, trim or reflector, and trim ring are visible from below, with the trim ring and lens sitting about flush against the sheetrock surface.